Best-selling author, TV host and personal finance guru Suze Orman has been inspiring Americans for decades to save wisely and make better money moves -- and avoid serious financial mistakes.
She'll be the first to tell you that what you don't do with your money may be even more important than what you do with it.
Here are 20 major money no-nos -- straight from the expert.
1. Don't be too quick to buy a home
Homeownership is part of the American dream — but buying one before you're able can lead to financial disaster.
"Sometimes it makes sense to own a home," Orman tells CNBC.com. "And sometimes, depending on where you live, it makes sense to simply rent."
That's particularly true if you're in an expensive city. Instead of pouring a lot of money into property, Orman says why not invest in the stock market? That way, you can grow your savings — maybe into a down payment on that home of your dreams.
A good way to get into investing is through an automated investment service, which will automatically adjust your portfolio to protect you from market turbulence.
2. Don't lease a car
In Suze Orman's words, you should "you should never, ever ever ever, lease a car."
If you lease, you'll sink your money into several years' worth of car payments and be empty-handed when the lease term is done.
Financing is a better option, but Orman says if it will take longer than three years to pay off the car, then it’s out of your price range. (You certainly don't want to consider one of today's seven-year car loans.)
Buying a used car is another way to go. Models that are just a few years old will have great safety specifications and the same audio-visual tech as a new car, at a fraction of the price.
3. Don't co-sign a loan
When a friend or family member in need asks you to co-sign a loan, Orman says the only correct response is to turn them down.
As she puts it: "Don’t be afraid to say 'no to others and say 'yes' to yourself."
When you co-sign a loan, you become legally responsible for paying back the money. Life is unpredictable, and if anything happens to prevent the borrower from repaying the loan, you’ll be on the hook to make the payments.
Plus, if the borrower is so much as late on a few payments, your credit score can take a hit.
4. Don't take Social Security too soon
Our favorite financial guru advises Americans to avoid early retirement for a very good reason: It's worth it to delay taking Social Security until age 70.
"Every year you wait between your normal retirement age and 70, Social Security will add a guaranteed 8% to your eventual monthly payout," she writes, in AARP The Magazine.
She says delaying Social Security until you reach 70 will give you a monthly benefit more than 75% percent higher than what you'll get if you start at 62.
"Living well into your 80s and beyond is no longer some rare event," Orman says — and you want to make sure your resources will last as long as you do.
5. Don't sell stocks when markets are bad
When stocks are hurtling lower, investors tend to drop investments fast. This is a bad idea, says Orman.
Instead of dumping stock, she advises that you just keep investing the same amount of money each month, regardless of what the market is doing. Using this strategy, a bad month for the market becomes a good month to invest.
"I wish for 2008 again," she tells Yahoo Finance, referring to the year of the big market meltdown. "That’s when the fortune was made. That’s when you could buy stocks for pennies on the dollar."
If you train yourself to hold on tight through market dips, you’ll continue to build a solid portfolio with long-term earning potential.
6. Don't put blind faith in a financial adviser
It's important to have a financial adviser you can trust.
"Don’t think that they’re always going to have your best interest at heart, because probably they have their own best interest at heart,” Orman says.
When selecting a financial professional, make sure he or she is a "fiduciary," which means your adviser has a legal duty to act in your best interest.
During your vetting process, ask prospective advisers about how they'll be compensated for working with you, and about other services they can offer. This will give you a good idea of their motivations when they invest your money.
7. Don't borrow from your 401(k)
Suze Orman calls borrowing money from your 401(k) "the biggest mistake you will ever make" with your retirement money, especially if you use the money to pay off other debt.
A 401(k) loan is better than withdrawing money from your account, which will bring you a tax bill and a 10% penalty if you're younger than age 59 1/2. Plus, the loans typically come with a lower interest rate than a traditional loan.
But you might be barred from putting more money into your 401(k) for six months, meaning you'll miss opportunities to make pre-tax contributions that lower your taxable income.
Even worse, by taking part of your retirement savings out of commission even temporarily, you'll lose out on significant earnings if markets rise.
8. Don't let debt linger
"Debt is bondage,” Orman tells CNBC. "You will never, ever, ever have financial freedom if you have debt."
Still, she points out that not all debt is the same.
Mortgages and student loans can be considered "good debt," because home loans usually have fairly low interest rates and your degree is an investment that should generate a higher income over time.
However, credit cards have much higher interest rates. The longer you put off paying down your credit balances, the more money you lose. You can easily wind up paying for your purchases three or four times over.
9. Don't spend to impress others
It's human nature to want to impress others. But Orman knows from experience how foolish that is.
She once leased a fancy BMW and bought a Cartier watch with money borrowed from her 401(k) — just to impress a woman she was dating. She says it was "the most stupid thing I’ve ever done with money."
In the end, spending money you don’t have to impress others will leave you with shallow relationships and stressful bills.
Work hard, invest wisely, and reap your fortune when you’ve made it. There’s nothing more impressive than true financial success.
10. Don't say it's impossible to save
Orman says too often she tells people they ought to consider saving more — only to have them respond that it's impossible because there's never any extra money left over at the end of the month.
"I beg to differ," she says, on SuzeOrman.com. "There’s no money left because you haven’t evaluated your spending habits. You need to dig deep and be willing to change those habits."
Practically anyone can squeeze out up to $100 in "hidden money" for saving and investing each month, Orman says.
For example, you might boost your home's energy efficiency and cut your utility bills by as much as 10% by caulking drafty windows, putting weather stripping around exterior doors, and switching to energy-saving lightbulbs.
11. Don't spend on things you don't really need
There’s no better way to kick-start your savings than by playing the need vs. want game.
The next time you're ready to buy something, ask yourself whether you really need it. Is it a necessity, such as medication, food from the grocery store or a solid pair of shoes for work?
Or simply something you want — like another drink at the bar, fast food for dinner again or a second pair of knee-high boots?
"If it’s a want, just walk away. If it’s a need, then buy it," Orman writes. "Try this for six months and you’ll be shocked at how easy it is and how much money you’ll save."
12. Don't retire too early
On a recent edition of the podcast Afford Anything, Orman was asked what she thought of the FIRE movement. That's FIRE as in "financial independence, retire early."
Her blunt response — “I hate it. I hate it. I hate it. I hate it" — set off a firestorm among the FIRE faithful.
But she explained that it would take a lot of money to make retirement work at, say, age 35.
"You need at least $5 million, or $6 million," she said. "Really, you might need $10 million." In her opinion, anything less wouldn't offer you enough protection from a potential financial catastrophe, like an expensive illness.
"You will get burned if you play with FIRE," Orman told her interviewer.
13. Don't go without a will
"Do you have your estate planning in place? If not, you might want to think again," Orman writes, on Oprah.com.
While everybody needs a will, most Americans don't have one and lack other important end-of-life documents, including a revocable living trust.
That's a legal arrangement that holds your property while you're alive and transfers it to your heirs after your death, without the complicated process known as probate.
Orman says set up a revocable living trust for passing down your house and other major assets, and draw up a will for your other special possessions, like great-grandma's wedding ring or your first-edition book collection.
14. Don't take out a reverse mortgage in your 60s
A reverse mortgage is a type of home equity loan for seniors that allows you to receive the money as a lump sum or in monthly installments. The loan is repaid — with interest — when you die or sell the house.
You can take out a reverse mortgage starting at age 62, but Orman says that's risky.
In her view, it's best to treat a reverse mortgage as a last resort for emergency money, and to wait as long as you possibly can before going that route.
"If you tap all your home equity through a reverse at 62 and then at 72 you realize you can’t really afford the home, you will have to sell the home," she says, "and you may end up giving most or all of the sale price back to the lender to settle up."
15. Don't miss out on matching money
If you have a 401(k) or other retirement plan through work, don't leave free money on the table! Make sure you're putting enough in so that you'll receive the full matching contribution from your employer.
Orman says your company might kick in 50 cents for every dollar you contribute, up to 6% of your salary.
"Under those terms, if the employee contributed $3,000, the employer would kick in another $1,500," she says, on Oprah.com. "Hello! That's a guaranteed 50% return on your investment."
So, raise your paycheck contributions and start maxing out the match today.
16. Don't stay at a job you hate
Suze Orman says polls show that two-thirds of workers aren't really into their jobs. And if you're in that group, you're selling yourself short.
"Staying in a job you don’t like is disrespectful to yourself, and your loved ones," Orman says, on her website. "There is no way you can tell me that doesn’t negatively impact your relationships."
But quitting may not be the answer. Before you start looking around for a new opportunity, see if the job you have can be modified to address whatever it is that makes you unhappy.
Just don't ever frame it that way when you meet with the boss or HR. Instead, tell the management you'd like to talk about how your job might be "tweaked" so you can be more productive.
17. Don't buy a new car
If you love being the first person to drive a brand-new car and you can never get enough of that new-car smell — well, you'll have to get over all of that, Orman says.
"The second you drive that car off the lot, it depreciates, 10%, 20%,” she tells CNBC. "Let somebody else get that depreciation."
Your home may appreciate in value, but that rarely happens with a car. So don't waste your money on new, but always buy used.
Then, keep your vehicle as long as you can: at least 10 years, and maybe even 15 or 20. Orman says that's how wealthy people do it — including herself.
18. Don't go without life insurance
About 4 in 10 adults have no life insurance, according to the industry research group LIMRA.
Orman says for parents in particular, life insurance is a product you can't afford to go without. It provides peace of mind, because it will protect your family if something happens to you and you're suddenly out of the picture.
And it's cheap: A healthy 40-year-old woman might pay less than $35 a month for a policy with a $500,000 death benefit. Orman recommends "level term" life insurance, meaning the premiums never change.
"C’mon Moms. (And Dads)," says the personal finance guru, on her site. "You can't tell me that less than one dollar a day is too much to ensure your family is safe no matter what."
19. Don't ever miss a student loan payment
Struggling with student loan debt? Whatever you do, don't just throw up your hands and stop paying.
"Make paying back your student loan the very first bill you pay," Orman says on her Facebook page. "It is more important that you make your student loan payments on time each month than any other bill."
She has called student loan debt "the most dangerous debt you can ever have" because you can't erase it through bankruptcy.
If you try to walk away from your loans, the debt will catch up with you eventually. The government can garnish your wages for federal student loan debt — in other words, take what you owe directly from your pay.
20. Don't invest for the wrong reasons
Orman says too many people — especially young people — make investment choices purely because a stock seems cool or trendy.
"They decide, 'This company is great, I'm going to invest in that,'" she tells CNBC.com. If that's your strategy, "maybe you'll hit it right, maybe you'll hit it wrong."
It's less risky to diversify your investing, by putting your money into index funds and exchange-traded funds, or ETFs.
Open an investing account and put in regular amounts, through what's called "dollar cost averaging." Stay steady through the market's ups and downs and you'll always come out ahead, Suze Orman says.
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